Bulk material, such as lime, carbon, slag formers, alloying elements, and the like, are rapidly charged in an electric arc furnace (EAF). Bulk material are delivered to the EAF through an open furnace roof. Preferably, the charging of the bulk material occurs during the period in which the furnace roof is open and receiving the scrap metals. The amount of time during which the roof is open, however, should be held to a minimum in order to minimize the amount of heat lost by the furnace and to decrease the production time.
Needs exist for a bulk material loader that allows a large quantity of non-scrap bulk material to be charged in a short period of time.
One type of existing material loading equipment for loading bulk material into an EAF utilizes a scrap charging bucket. The scrap charging bucket carries both scrap and bulk material. Consequently, use of the scrap charging bucket causes the bulk material to be charged simultaneously with the scrap. Use of the scrap charging bucket has numerous drawbacks. When the bulk material is charged along with the scrap, some of the bulk material is carried away with the thermal flow of furnace off-gases. This loss of bulk material decreases the amount of material available for the metal melting and refining process. It also increases the particulate material that must be removed and treated by associated environmental pollution equipment and increases the amount of fugitive particles entering the shop environment.
Another type of existing material loading equipment for loading bulk material into an EAF utilizes large sacks that are carried to the furnace and emptied through an open roof of the furnace. This process has numerous drawbacks. For example, this process requires that the furnace roof be opened for an extended period of time which raises numerous environmental concerns. Also, this process often requires that multiple sacks be used. This leads to an increase in furnace downtime since the material handling equipment must discard the remains of the used sack before retrieving another sack. Finally, the use of sacks is expensive.
Other existing bulk material loading equipment requires that a slag door be opened and that the bulk material be charged through the slag door opening. When the bulk material is charged through the slag doorway, the slag door must be kept open. As a consequence, this procedure allows excessive infiltration of ambient air which results in an undesirable decrease in the internal temperature of the furnace. Furthermore, the excessive infiltration of ambient air into the furnace resulting from this procedure decreases the efficiency of the air/gas pollution control equipment.